Extended wear-time dressing

ABSTRACT

As an example, in some embodiments is a dressing that may comprise a manifold, a bioresorbable component, and a degradation-modulating component. The degradation-modulating component may cover two or more surfaces of the bioresorbable component. The degradation-modulating component may be further configured to modulate degradation of the bioresorbable component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional filing of U.S. National Stage Entry ofSer. No. 16/759935, filed Apr. 28, 2020, which claims the benefit of PCTPublication No. PCT/US2018/056914, filed Oct. 22, 2018, which claims thebenefit, under 35 USC § 119(e), of the filing of U.S. Provisional PatentApplication Ser. No. 62/581,540, entitled “Extended Wear-Time Dressing,”filed Nov. 3, 2017, all of which are incorporated by reference in theirentirety.

TECHNICAL FIELD

The invention set forth in the appended claims relates generally totreatment of a tissue site and, more particularly, but with limitation,to dressings for application to a tissue site, to systems including suchdressings and to methods related to the same.

BACKGROUND

Clinical studies and practice have shown that reducing pressure inproximity to a tissue site can augment and accelerate growth of newtissue at the tissue site. The applications of this phenomenon arenumerous, but it has proven particularly advantageous for treatingwounds. Regardless of the etiology of a wound, whether trauma, surgery,or another cause, proper care of the wound is important to the outcome.Treatment of wounds or other tissue with reduced pressure may becommonly referred to as “negative-pressure therapy,” but is also knownby other names, including “negative-pressure wound therapy,”“reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,”and “topical negative pressure,” for example. Negative-pressure therapymay provide a number of benefits, including migration of epithelial andsubcutaneous tissues, improved blood flow, and micro-deformation oftissue at a wound site. Together, these benefits can increasedevelopment of granulation tissue and reduce healing times.

While the clinical benefits of negative-pressure therapy are widelyknown, improvements to therapy systems, components, and processes maybenefit healthcare providers and patients.

BRIEF SUMMARY

Systems, apparatuses such as a dressing, and methods for using the same,for example, in a negative-pressure therapy environment, are set forthin the appended claims. Illustrative embodiments are also provided toenable a person skilled in the art to make and use the claimed subjectmatter.

For example, in some embodiments a dressing having an extended wear-timemay include one or more dressing layers or components, and at least onecomponent for modulating the degradation of other components or layers.Such dressings may be suitable for negative-pressure therapy systems insome embodiments.

Some embodiments of a dressing may comprise a manifold, a bioresorbablecomponent, and degradation-modulating component. In some embodiments,the degradation-modulating component may be configured to modulatedegradation of at least one of the bioresorbable component. In someembodiments, the bioresorbable component may comprise collagen andoxidized, regenerated cellulose. In some embodiments, thedegradation-modulating component may comprise a polymer having one ormore monomeric units. In some embodiments the monomeric unit present inthe polymer may be derived from another monomeric unit that has beenmodified, for example, functionalized, after polymerization. Themonomeric repeating unit may comprise vinyl pyrrolidone, vinyl alcohol(for example, which may be derived from vinyl acetate), ethylene oxide,propylene oxide, ethylene glycol, acrylic acid, a salt of acrylic acid,an ester of acrylic acid, acrylamido methylpropane sulphonic acid, asalt of acrylamido methylpropane sulphonic acid, an ester of acrylamidomethylpropane sulphonic acid, cellulose derivatives, copolymers thereof,blends or mixtures thereof, or combinations thereof. For example, thepolymer may comprise polyvinyl pyrrolidone, polyvinyl alcohol,polyethylene glycol, polypropylene glycol, poly(acrylic acid), orpoly(acrylamido methylpropane sulphonic acid).

In some embodiments, a system for providing negative-pressure therapy toa tissue site may comprise a dressing. The dressing may comprise amanifold, a bioresorbable component, and a degradation-modulatingcomponent. In some embodiments, the degradation-modulating component maybe configured to modulate degradation of the bioresorbable component. Insome embodiments, the bioresorbable component may comprise collagen andoxidized, regenerated cellulose. In some embodiments, thedegradation-modulating component may comprise a polymer having one ormore monomeric units. In some embodiments the monomeric unit present inthe polymer may be derived from another monomeric unit that has beenmodified, for example, functionalized, after polymerization. Themonomeric unit may comprise vinyl pyrrolidone, vinyl alcohol (forexample, which may be derived from vinyl acetate), ethylene oxide,propylene oxide, ethylene glycol, acrylic acid, a salt of acrylic acid,an ester of acrylic acid, acrylamido methylpropane sulphonic acid, asalt of acrylamido methylpropane sulphonic acid, an ester of acrylamidomethylpropane sulphonic acid, cellulose derivatives, copolymers thereof,blends or mixtures thereof, or combinations thereof. For example, thepolymer may comprise polyvinyl pyrrolidone, polyvinyl alcohol,polyethylene glycol, polypropylene glycol, poly(acrylic acid), orpoly(acrylamido methylpropane sulphonic acid). The system may alsocomprise a negative-pressure source configured to be fluidly coupled tothe manifold.

Example embodiments of methods for providing negative-pressure therapyto a tissue site are also described. A method may comprise, for example,positioning dressing including a manifold, a component, and adegradation-modulating component proximate to the tissue site. Thedressing may be positioned such that the degradation-modulatingcomponent may be configured to modulate degradation of the bioresorbablecomponent. In some embodiments, the bioresorbable component may comprisecollagen and oxidized, regenerated cellulose. In some embodiments, atleast one of the degradation-modulating component may comprise a polymerhaving one or more monomeric repeating units. In some embodiments themonomeric repeating unit present in the polymer may be derived fromanother monomeric unit that has been modified, for example,functionalized, after polymerization. The monomeric repeating unit maycomprise vinyl pyrrolidone, vinyl alcohol (for example, which may bederived from vinyl acetate), ethylene oxide, propylene oxide, ethyleneglycol, acrylic acid, a salt of acrylic acid, an ester of acrylic acid,acrylamido methylpropane sulphonic acid, a salt of acrylamidomethylpropane sulphonic acid, an ester of acrylamido methylpropanesulphonic acid, cellulose derivatives, copolymers thereof, blends ormixtures thereof, or combinations thereof. For example, the polymer maybe polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol,polypropylene glycol, poly(acrylic acid), or poly(acrylamidomethylpropane sulphonic acid). The method may also comprise placing asealing member over the dressing. The method may also comprise sealingthe sealing member to tissue surrounding the tissue site to form asealed space. The method may also comprise fluidly coupling a negativepressure source to the sealed space. The method may also compriseoperating the negative pressure source to draw fluid from the tissuesite and generate a negative pressure in the sealed space.

Objectives, advantages, and a preferred mode of making and using theclaimed subject matter may be understood best by reference to theaccompanying drawings in conjunction with the following detaileddescription of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic of an example embodiment of anegative-pressure therapy system including a dressing in accordance withthis specification.

FIG. 2 is a partial cut-away view of an example embodiment of adressing.

FIG. 3 is a partial cut-away view of an example embodiment of adressing.

FIG. 4 is a partial cut-away view of an example embodiment of adressing.

FIG. 5 is a partial cut-away view of an example embodiment of adressing.

FIG. 6 is a partial cut-away view of an example embodiment of adressing.

It should be noted that the figures set forth herein are intended toillustrate the general characteristics of certain example embodiments.The figures may not precisely reflect the characteristics of any givenembodiment, and are not necessarily intended to define or limit thescope of the claimed subject matter.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides informationthat enables a person skilled in the art to make and use the subjectmatter set forth in the appended claims, but may omit certain detailsalready well-known in the art. The following detailed description is,therefore, to be taken as illustrative and not limiting.

The example embodiments may also be described herein with reference tospatial relationships between various elements or to the spatialorientation of various elements depicted in the attached drawings. Ingeneral, such relationships or orientation assume a frame of referenceconsistent with or relative to a patient in a position to receivetreatment. However, as should be recognized by those skilled in the art,this frame of reference is merely a descriptive expedient rather than astrict prescription.

For example, FIG. 1 illustrates an embodiment of a system 100 configuredto provide negative pressure to a tissue site in accordance with thedisclosure of this specification.

As used herein the term “tissue site” is intended to broadly refer to awound, defect, or other treatment target located on or within tissue,including but not limited to, bone tissue, adipose tissue, muscletissue, neural tissue, dermal tissue, vascular tissue, connectivetissue, cartilage, tendons, or ligaments. A wound may include chronic,acute, traumatic, subacute, and dehisced wounds, partial-thicknessburns, ulcers (such as diabetic, pressure, or venous insufficiencyulcers), flaps, and grafts, for example. The term “tissue site” may alsorefer to areas of any tissue that are not necessarily wounded ordefective, but are instead areas in which it may be desirable to add orpromote the growth of additional tissue.

In various embodiments, the system 100 generally includes anegative-pressure supply, and may include or be configured to be coupledto a distribution component, such as a dressing. In general, adistribution component may refer to any complementary or ancillarycomponent configured to be fluidly coupled to a negative-pressure supplyin a fluid path between a negative-pressure supply and a tissue site. Adistribution component may be detachable and, as well, may bedisposable, reusable, or recyclable. For example, in some embodiments,the system 100 may include a dressing 102 that is illustrative of adistribution component fluidly coupled to a negative-pressure source104.

The fluid mechanics associated with using a negative-pressure source toreduce pressure in another component or location, such as within asealed therapeutic environment, can be mathematically complex. However,the basic principles of fluid mechanics applicable to negative-pressuretherapy are generally well-known to those skilled in the art. Theprocess of reducing pressure may be described generally andillustratively herein as “delivering,” “distributing,” “providing,” or“generating” negative pressure, for example.

In general, a fluid, such as wound fluid (for example, wound exudatesand other fluids), flow toward lower pressure along a fluid path. Thus,the term “downstream” typically implies something in a fluid pathrelatively closer to a source of negative pressure or further away froma source of positive pressure. Conversely, the term “upstream” impliessomething relatively further away from a source of negative pressure orcloser to a source of positive pressure. Similarly, it may be convenientto describe certain features in terms of a fluid “inlet” or “outlet” insuch a frame of reference. This orientation is generally presumed forpurposes of describing various features and components herein. However,the fluid path may also be reversed in some applications (such as bysubstituting a positive-pressure source for a negative-pressure source)and this descriptive convention should not be construed as a limitingconvention.

As used herein, “negative pressure” is generally intended to refer to apressure less than a local ambient pressure, such as the ambientpressure in a local environment external to a sealed therapeuticenvironment provided by the dressing 102. In many cases, the localambient pressure may also be the atmospheric pressure proximate to orabout a tissue site. Alternatively, the pressure may be less than ahydrostatic pressure associated with the tissue at the tissue site.Unless otherwise indicated, values of pressure stated herein are gaugepressures. Similarly, references to increases in negative pressuretypically refer to a decrease in absolute pressure (e.g., a “morenegative” pressure), while decreases in negative pressure typicallyrefer to an increase in absolute pressure (e.g., a “less negative”pressure or a “more positive” pressure). While the amount and nature ofnegative pressure applied to a tissue site may vary according totherapeutic requirements, the pressure is generally a low vacuum, alsocommonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and−500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −50 mm Hg(−6.7 kPa) and −300 mm Hg (−39.9 kPa).

In various embodiments, a negative-pressure supply, such as thenegative-pressure source 104, may be a reservoir of air at a negativepressure, or may be a manual or electrically-powered device that canreduce the pressure in a sealed volume, such as a vacuum pump, a suctionpump, a wall suction port available at many healthcare facilities, or amicro-pump, for example. A negative-pressure supply may be housed withinor used in conjunction with other components, such as sensors,processing units, alarm indicators, memory, databases, software, displaydevices, or user interfaces that further facilitate therapy. Forexample, in some embodiments, the negative-pressure source may becombined with one or more other components into a therapy unit. Anegative-pressure supply may also have one or more supply portsconfigured to facilitate coupling and de-coupling of thenegative-pressure supply to one or more distribution components.

In some embodiments, the system 100 may include a controller 110. Thecontroller 110 may also be coupled to the negative-pressure source 104.The controller 110 may generally be configured to control one or moreoperational parameters associated with the negative-pressure therapysystem. In some embodiments, the system 100 may include one or moresensors, for example, to measure operating parameters and providefeedback signals indicative of those operating parameters to acontroller like the controller 110. A controller, such as the controller110, may be a microprocessor or computer programmed to operate one ormore components of the system 100, such as the negative-pressure source104. In some embodiments, for example, the controller 110 may be amicrocontroller, which generally comprises an integrated circuitcontaining a processor core and a memory programmed to directly orindirectly control one or more operating parameters of the system 100.Operating parameters may include the power applied to thenegative-pressure source 104, the pressure generated by thenegative-pressure source 104, or the pressure distributed to thedressing 102, for example. The controller 110 may also be configured toreceive one or more input signals, such as an input signal from a userinterface.

In some embodiments, the negative-pressure source 104 may be operativelycoupled to the dressing 102 via a dressing interface. In someembodiments, the system 100 may include a fluid container, such as acontainer 112, fluidly coupled to the dressing 102 and to thenegative-pressure source 104. The container 112 is representative of acontainer, canister, pouch, or other storage component, which can beused to manage exudates and other fluids withdrawn from a tissue site.In many environments, a rigid container may be preferred or required forcollecting, storing, and disposing of fluids. In other environments,fluids may be properly disposed of without rigid container storage, anda re-usable container could reduce waste and costs associated withnegative-pressure therapy.

In various embodiments, components may be fluidly coupled to each otherto provide a path for transferring fluids (i.e., liquid and/or gas)between the components. For example, components may be fluidly coupledthrough a fluid conductor, such as a tube. As used herein, the term“tube” is intended to broadly include a tube, pipe, hose, conduit, orother structure with one or more lumina adapted to convey a fluidbetween two ends thereof. Typically, a tube is an elongated, cylindricalstructure with some flexibility, but the geometry and rigidity may vary.In some embodiments, two or more components may also be coupled byvirtue of physical proximity, being integral to a single structure, orbeing formed from the same piece of material. Moreover, some fluidconductors may be molded into or otherwise integrally combined withother components. Coupling may also include mechanical, thermal,electrical, or chemical coupling (such as a chemical bond) in somecontexts. For example, a tube may mechanically and fluidly couple thedressing 102 to the container 112 in some embodiments. In general,components of the system 100 may be coupled directly or indirectly. Forexample, the negative-pressure source 104 may be directly coupled to thecontroller 110, and may be indirectly coupled to the dressing 102, forexample, through the container 112.

Dressing

Often, in the context of negative-pressure therapy, negative pressuremay be applied to a tissue site via materials and devices generallycharacterized as “dressings.” Generally, in addition to providing forthe application of negative pressure to a tissue site, dressings maycontrol bleeding, ease pain, assist in debriding, protect tissue frominfection, modulate protease activity, or otherwise promote healing andprotect the tissue site from damage.

In some embodiments, the fluid pathways of a manifold may beinterconnected to improve distribution or collection of fluids. In someembodiments, a manifold may be a porous foam material having a pluralityof interconnected cells or pores. For example, open-cell foams,including reticulated foams, generally include pores, edges, and/orwalls adapted to form interconnected fluid pathways, such as channels.In various embodiments, foam-forming materials may be formed into foam,such as by curing, so as to include various apertures and fluidpathways. In some embodiments, a manifold may additionally oralternatively comprise projections that form interconnected fluidpathways. For example, a manifold may be molded to provide surfaceprojections that define interconnected fluid pathways.

In various embodiments, the dressing 102 may be generally configured todistribute negative pressure, for example, so as to collect fluid. Forexample, the dressing 102 may comprise or be configured as a manifold. A“manifold” in this context generally includes any composition orstructure providing a plurality of pathways configured to collect ordistribute fluid across a tissue site under pressure. For example, amanifold may be configured to receive negative pressure from anegative-pressure source and to distribute negative pressure throughmultiple apertures (pores), which may have the effect of collectingfluid and drawing the fluid toward the negative-pressure source. Forexample, in some embodiments the dressing 102 may be configured toreceive negative pressure from the negative-pressure source 104 and todistribute the negative pressure through a sealed space 107, forexample, which may have the effect of collecting fluid from the tissuesite. In additional or alternative embodiments, the fluid path may bereversed or a secondary fluid path may be provided to facilitatemovement of fluid across a tissue site.

In some embodiments, a dressing may generally comprise one or morecomponents configured to interface with a tissue site or to perform anyof a variety of functions. For example, in some embodiments the dressing102 may comprise a cover 106 and a manifold 120. The dressing 102 mayalso comprise at least one bioresorbable component 130, at least onedegradation-modulating component 140, or some combination of at leastone bioresorbable component 130 and at least one degradation-modulatingcomponent 140. In some embodiments, the dressing 102 may comprise one,two, three, four, five, six, seven, eight, or more bioresorbablecomponents 130. Also, in some embodiments, the dressing 102 may compriseone, two, three, four, five, six, seven, eight, or moredegradation-modulating components 140. In various embodiments, thebioresorbable component 130 and the degradation-modulating component 140may be present in any suitable number of layers. For example, in someembodiments, the bioresorbable component 130 and thedegradation-modulating component 140 may be present as separate layers.In some embodiments the bioresorbable component 130 and thedegradation-modulating component 140 may be incorporated within a singlelayer.

Dressing—Cover

In various embodiments, the cover 106 may generally be configured toprovide a bacterial barrier and protection from physical trauma. Thecover 106 may also be constructed from a material that can reduceevaporative losses and provide a fluid seal between two components ortwo environments, such as between a therapeutic environment and a localexternal environment. The cover 106 may be, for example, an elastomericfilm or membrane that can provide a seal adequate to maintain a negativepressure at a tissue site for a given negative-pressure source. In someembodiments, the cover 106 may have a high moisture-vapor transmissionrate (MVTR). For example, the MVTR may be at least 300 g/m² pertwenty-four hours. In some embodiments, the cover 106 may be formed froma suitable polymer. For example, the cover 106 may comprise a polymerdrape, such as a polyurethane film, which may be permeable to watervapor but generally impermeable to liquid. In such embodiments, thecover 106 may have a thickness in the range of about from 25 to about 50microns. In embodiments where the cover comprises a permeable material,the cover 106 may have a sufficiently low permeability that a desirednegative pressure may be maintained.

In some embodiments, the cover 106 may be configured to be attached toan attachment surface, such as undamaged epidermis, a gasket, or anothercover, for example, via an attachment device. For example, in someembodiments the cover may be attached to epidermis so as to form thesealed space 107. In such an embodiment, the attachment device may takeany suitable form. For example, an attachment device may be amedically-acceptable, pressure-sensitive adhesive that extends about aperiphery, a portion, or an entire sealing member. In some embodiments,for example, some or all of the cover 106 may be coated with anadhesive, such as an acrylic adhesive, having a coating weight between25-65 grams per square meter (g.s.m.). Thicker adhesives, orcombinations of adhesives, may be applied in some embodiments, forexample, to improve the seal and reduce leaks. Other example embodimentsof an attachment device may include a double-sided tape, a paste, ahydrocolloid, a hydrogel, a silicone gel, or an organogel.

Dressing—Manifold

In some embodiments, the manifold 120 may comprise or consistessentially of foam, for example, a reticulated foam, or combinationsthereof. In various embodiments, the average pore size of the foam mayvary according to needs of a prescribed therapy. The tensile strength ofthe manifold 120 may also vary according to needs of a prescribedtherapy.

In some embodiments, the manifold 120 may be foam characterized bydensity. In some embodiments, the manifold 120 may be characterized as arelatively dense material. For example, in various embodiments, themanifold 120 may have a density of from about 24 kg/m³ to about 125kg/m³ or, in a more particular embodiment, from about 24 kg/m³ to about72 kg/m³. Additionally or alternatively, the manifold 120 may also becharacterized as exhibiting a particular porosity and/or pore size. Thenumber of pores and the average pore size of the manifold 120 may varyaccording to needs of a prescribed therapy. For example, in variousembodiments, the manifold 120 may be characterized as exhibiting aporosity of from about 20 pores per inch to about 120 pores per inch.Additionally, in various embodiments, the manifold 120 may have anaverage pore size in a range of from about 400 to about 600 microns.

In some embodiments, the manifold 120 may be characterized ashydrophobic. For example, the manifold 120 may be characterized as ahydrophobic, open-cell foam. Not intending to be bound by theory, insuch embodiments, the hydrophobic characteristics may prevent themanifold 120 from directly absorbing fluid, such as wound exudate from atissue site, but may allow the fluid to pass, for example, through theinternal structure. For example, in some embodiments, the manifold 120may be a hydrophobic, open-cell polyurethane foam, a silicone foam, apolyether block amide foam, such as PEBAX®, an acrylic foam, a polyvinylchloride (PVC) foam, a polyolefin foam, a polyester foam, a polyamidefoam, a thermoplastic elastomer (TPE) foam such as a thermoplasticvulcanizate (TPV) foam, other crosslinked elastomeric foams such asfoams formed from styrene-butadiene rubber (SBR) and ethylene propylenediene monomer (EPDM) rubber, or combinations thereof. Examples of a foamsuitable for use as the manifold 120 include the foam used in theV.A.C.® GRANUFOAM™ Dressing commercially-available from KCI in SanAntonio, Texas.

In some alternative embodiments, the manifold 120 may be characterizedas hydrophilic. Not intending to be bound by theory, in suchembodiments, the manifold 120 may be effective to wick fluid while alsocontinuing to distribute negative pressure to a tissue site. In suchembodiments, the wicking properties of the manifold 120 may draw fluidaway from a tissue site by capillary flow or other wicking mechanisms.An example of hydrophilic foam may include a polyvinyl alcohol orpolyether, open-cell foam. Other foams that may exhibit hydrophiliccharacteristics include hydrophobic foams that have been treated orcoated to provide hydrophilicity. For example, the manifold 120 may be atreated open-cell polyurethane foam.

Bioresorbable Component

In some embodiments, the bioresorbable component 130 may becharacterized as biodegradable or as exhibiting biodegradability. Asused herein, “biodegradable” and “biodegradability” may refer to acharacteristic of a material to at least partially break down uponexposure to physiological fluids or processes. For example, in someembodiments, the bioresorbable component 130 may disintegrate, degrade,or dissolve when contacted with an aqueous medium, such as water, blood,or wound exudate from a tissue site. Biodegradability may be a result ofa chemical process or condition, a physical process or condition, orcombinations thereof.

Additionally or alternatively, in some embodiments, the bioresorbablecomponent 130 may be characterized as bioresorbable or as exhibitingbioresorbability. As used herein, “bioresorbable” and “bioresorbability”may refer to a characteristic of a material to be broken down intodegradation products that may be absorbed at a tissue site so as to beeliminated by the body, for example via metabolism or excretion. In someembodiments the bioresorbability characteristics of the bioresorbablecomponent 130 may be such that at least a portion of the bioresorbablecomponent 130 or the material from which the bioresorbable component 130is formed may be eliminated from the tissue site to which it is appliedby bioresorption.

In some embodiments, the bioresorbable component 130 may be configuredto exhibit a particular proportion of disintegration, degradation, ordissolution within a particular time period. For instance, in variousembodiments, the bioresorbable component 130 may be configured such thatabout 90% by weight, or about 95% by weight, or about 99% by weight, orabout 100% by weight of a particular bioresorbable component 130 may bedisintegrated, degraded, or dissolved within a time period of from about6 hours to about 48 hours, or from about 12 hours to about 36 hours, orfrom about 18 hours to about 24 hours, from contact with a physiologicalfluid, for example, an aqueous fluid such as blood or wound exudate, ata temperature of about 37° C.

In some embodiments, the bioresorbable component 130 may comprise asuitable structure, for example, a film, foam such as open-cell foam, afibrous substrate such as a woven or non-woven mesh, or combinationsthereof. In various embodiments, suitable foam may an average pore sizethat can vary according to needs of a prescribed therapy. For example,the bioresorbable component 130 may comprise foam having pore sizes in arange of 400-600 microns. Additionally, a suitable film or foam may havevarious physical properties, such as tensile strength, as will besuitable according to needs of a prescribed therapy.

In some embodiments, the bioresorbable component 130 may comprise or beformed at least partially from a suitable composition, which may bereferred to herein as a bioresorbable composition. For example, thebioresorbable composition may make up at least some part of an open-cellfoam or film of the bioresorbable component 130.

In some embodiments, the bioresorbable composition comprises oxidizedcellulose or, in a more particular embodiment, oxidized regeneratedcellulose (ORC). Oxidized cellulose may be produced by the oxidation ofcellulose, for example with dinitrogen tetroxide. Not intending to bebound by theory, this process may convert primary alcohol groups on thesaccharide residues to carboxylic acid group, forming uronic acidresidues within the cellulose chain. The oxidation may not proceed withcomplete selectivity, and as a result hydroxyl groups on carbons 2 and 3may be converted to the keto form. These ketone units yield an alkalilabile link, which at pH 7 or higher initiates the decomposition of thepolymer via formation of a lactone and sugar ring cleavage. As a result,oxidized cellulose may be biodegradable and bioresorbable underphysiological conditions.

In some embodiments, the oxidized cellulose may be ORC prepared byoxidation of a regenerated cellulose, such as rayon. ORC may bemanufactured, for example, by the process described in U.S. Pat. No.3,122,479 to Smith, issued Feb. 24, 1964, which is incorporated hereinby reference in its entirety. ORC is available with varying degrees ofoxidation and hence rates of degradation. In some embodiments, the ORCmay be in the form of water-soluble low molecular weight fragmentsobtained by alkali hydrolysis of ORC.

The ORC may be used in a variety of physical forms, including particles,fibers, sheets, sponges, or fabrics. In some embodiments, the ORC is inthe form of particles, such as fiber particles or powder particles, forexample dispersed in a suitable solid or semisolid topical medicamentvehicle. In some embodiments, the bioresorbable composition comprisesORC fibers, for example, having a volume fraction of at least 80% of thefibers have lengths in the range of from about 20 μm to about 50 mm. Insome embodiments, a volume fraction of at least 80% of the fibers havelengths in the range of from about 5 μm to about 1000 μm, or from about250 μm to about 450 μm. In some embodiments, a volume fraction of atleast 80% of the fibers have lengths in the range of from about 25 mm toabout 50 mm. Desired size distributions can be achieved, for example, bymilling an ORC cloth, followed by sieving the milled powder to removefibers outside the range. Fabrics may include woven, non-woven andknitted fabrics.

The ORC may be present in the bioresorbable composition at any levelappropriate to result in the desired absorbency and rheologicalcharacteristics of the bioresorbable composition and/or thebioresorbable component. For example, the ORC may be present in thebioresorbable component at a level of from about 10% to about 80% byweight, or from about 30% to about 60% by weight, or from about 40% toabout 50% by weight, or about 45% ORC by weight of the bioresorbablecomponent.

In some embodiments, the bioresorbable composition comprises astructural protein. Examples of suitable structural proteins mayinclude, but are not limited to fibronectin, fibrin, laminin, elastin,collagen, gelatins, keratin, and mixtures thereof. For instance, in aparticular embodiment, the structural protein comprises, or is,collagen. The collagen may be obtained from any natural source. Thecollagen may be Type I, II or III collagen, or may also be chemicallymodified collagen, for example, an atelocollagen obtained by removingthe immunogenic telopeptides from natural collagen. The collagen mayalso comprise solubilized collagen or soluble collagen fragments havingmolecular weights in the range of from about about 100,000 or from about10,000 to about 50,000, which may be obtained, for example, by pepsintreatment of natural collagen. In various embodiments, the collagen isobtained from bovine corium that has been rendered largely free ofnon-collagenous components. Such non-collagenous components include fat,non-collagenous proteins, polysaccharides and other carbohydrates, asdescribed in U.S. Pat. No. 4,614,794, Easton et al., issued Sep. 30,1986 and U.S. Pat. No. 4,320,201, Berg et al., issued Mar. 16, 1982,incorporated by reference herein.

The collagen or other structural protein may be present in thebioresorbable composition at any level appropriate. For example, thecollagen or other structural protein may be present in the bioresorbablecomposition at a level of from about 20% to about 90% by weight, or fromabout 40% to about 70% by weight, or from about 50% to about 60%, orabout 55% collagen by weight of the bioresorbable component.

In some, more particular embodiments, the bioresorbable compositioncomprises both ORC and collagen. For example, in some embodiments, thebioresorbable component comprises ORC at a level of from about 40% toabout 50%, or about 45%, and collagen at a level of from about 50% toabout 60%, or about 55%, by weight of the bioresorbable component.

Additionally, in some embodiments the bioresorbable composition maycomprise one or more additional, optional materials. Such optionalcomponents may include, for example, preservatives, stabilizing agents,hydrogels and other gelling agents, plasticizers, matrix strengtheningmaterials, dyestuffs, and various active ingredients. In variousembodiments, the additional, optional materials may each, when present,be present in a safe and effective amount. As referred to herein, a“safe and effective” amount of a material used herein, refers to anamount that is sufficient to impart a desired effect without undueadverse side effects (such as toxicity, irritation, or allergicresponse), commensurate with a reasonable benefit/risk ratio when usedin the manner of this technology. The specific safe and effective amountof a particular material may vary with such factors as the type andquantity of other materials in the composition, the intended use, andthe physical condition of the subject to whom the bioresorbablecompositions are given, and the form in which the bioresorbablecompositions are employed.

For example, in some embodiments, the bioresorbable composition maycomprise an optional gelling agent, examples of which may include, butare not limited to polyurethane gels, modified acrylamide polymers, andhydrophilic polysaccharides. Examples of hydrophilic polysaccharides mayinclude, but are not limited to, alginates, chitosan, chitin, guar gums,pectin, polyethylene glycols, dextrans, starch derivatives, cellulosederivatives (such as hydroxyethyl cellulose, hydroxylpropyl cellulose,and hydroxypropylmethyl cellulose), glycosaminoglycans, galactomannans,chondroitin salts (such as chondroitin sulfate), heparin salts (such asheparin sulfate), hyaluroinic acid and salts thereof, hyaluronates, andmixtures thereof.

In some embodiments, the bioresorbable composition may comprisecarboxymethyl cellulose (“CMC”), for example, to modify the rheological,absorbency, or other characteristics of the bioresorbable composition orthe bioresorbable component. The CMC may be derived from cellulose andmodified such that carboxymethyl groups are bonded to hydroxyl groups inthe glucopyranose monomers that make up the cellulose. The CMC may be insalt form, for example, comprising a physiologically acceptable cation,such as sodium (i.e., sodium carboxymethyl cellulose). CMC iscommercially available as Walocel™ (sold by The Dow Chemical Company)and Cekol® (sold by CP Kelco). When present, the CMC may be present inthe bioresorbable composition at any level appropriate to result in thedesired characteristics.

In some embodiments, the bioresorbable composition comprises astrengthening material, which can improve the handling characteristicsof a bioresorbable component 130. For example, a strengthening materialcan decrease a substrate's susceptibility to tearing. An example of asuitable strengthening material includes non-gelling cellulose fibers.Such “non-gelling” cellulose fibers may be substantiallywater-insoluble, and may be produced from cellulose that has not beenchemically modified to increase water solubility (as contrasted fromcarboxymethyl cellulose or other cellulose ethers). Non-gellingcellulose fibers are commercially available as Tencel® fibers (sold byLenzing AG). Such fibers may be processed from a commercially-availablecontinuous length, by cutting into lengths that are, in someembodiments, from about 0.5 to about 5 cm, or from about 2 to about 3 cmin length. The non-gelling cellulose fibers may be present in thebioresorbable composition at any level appropriate to result in thedesired physical characteristics of the bioresorbable component.

In some embodiments, the bioresorbable composition may also comprise oneor more active ingredients, for example, which aid in wound healing.Examples of active ingredients include, but are not limited to,non-steroidal anti-inflammatory drugs, acetaminophen, steroids, optionalantibiotics and antiseptics (e.g., silver and chlorhexidine), growthfactors (e.g. fibroblast growth factor or platelet derived growthfactor), peptides, and microRNA. In general, such active ingredients,when present may be present at a level of from about 0.1% to about 10%by weight. As an example, the bioresorbable composition may comprise agrowth factor. Examples of suitable growth factors include, but are notlimited to, platelet derived growth factor (PDGF), fibroblast growthfactor (FGF), and epidermal growth factor (EGF), and mixtures thereof.

For example, the bioresorbable composition may comprise an antimicrobialagent, an antiseptic, or both. Examples of antimicrobial agents include,but are not limited to, tetracycline, penicillins, terramycins,erythromycin, bacitracin, neomycin, polymycin B, mupirocin, clindamycin,and combinations thereof. Examples of antiseptics include, but are notlimited to silver, polyhexanide (polyhexamethylene biguanide or PHMB),chlorhexidine, povidone iodine, triclosan, sucralfate, quaternaryammonium salts, and combinations thereof. For example, in variousembodiments, the bioresorbable composition may comprise silver, whichmay be in metallic form, in ionic form (e.g., a silver salt), or both.For example, the silver may be present in ionic form. In someembodiments, the bioresorbable composition may comprise a complex ofsilver and ORC (a “Silver/ORC complex”). As referred to herein, such acomplex may refer to an intimate mixture at the molecular level, forexample, with ionic or covalent bonding between the silver and the ORC.For example, the Silver/ORC complex may comprise a salt formed betweenthe ORC and Ag⁺, but it may also comprise silver clusters or colloidalsilver metal, for example produced by exposure of the complex to light.The complex of an anionic polysaccharide and silver can be made bytreating the ORC with a solution of a silver salt. In variousembodiments, the silver salt may be the salt of silver with a weak acid.Silver/ORC complexes useful herein, and methods of producing suchcomplexes, are described in U.S. Pat. No. 8,461,410, Cullen et al.,issued Jun. 11, 2013, incorporated by reference herein. Similarprocesses are described in U.S. Pat. No. 5,134,229, Saferstein et al.,issued Jul. 28, 1992, incorporated by reference herein. In variousembodiments, the Silver/ORC Complex may be present in the bioresorbablecomponent at a level of from about 1% to about 2% by weight of thebioresorbable component. Alternatively, in other embodiments, thebioresorbable composition does not contain an antimicrobial agent or anantiseptic.

In some embodiments, such as in embodiments where the bioresorbablecomposition comprises silver, the bioresorbable composition may comprisea dyestuff. The dyestuff may be light-absorbing in the visible region400-700 nm. Such dyestuffs may be operable to photochemically trapgenerated free radicals that could otherwise react with the silver inthe present compositions, acting as photochemical desensitisers. Invarious embodiments, the antioxidant dyestuff may be selected from thegroup consisting of aniline dyes, acridine dyes, thionine dyes,bis-naphthalene dyes, thiazine dyes, azo dyes, anthraquinone dyes, andmixtures thereof. For example, the antioxidant dyestuff may be selectedfrom the group consisting of gentian violet, aniline blue, methyleneblue, crystal-violet, acriflavine, 9-aminoacridine, acridine yellow,acridine orange, proflavin, quinacrine, brilliant green, trypan blue,trypan red, malachite green, azacrine, methyl violet, methyl orange,methyl yellow, ethyl violet, acid orange, acid yellow, acid blue, acidred, thioflavin, alphazurine, indigo blue, methylene green, and mixturesthereof. If present, the dyestuff may be present in the bioresorbablecomponent at a level of about 0.05% to about 5%, or about 0.2% to about2% by weight of the bioresorbable component.

In some embodiments, the bioresorbable composition may be configured toexhibit or impart one or more beneficial or adverse effects whendeployed in a physiological environment (e.g., a tissue site), forexample, protease-inhibiting activity, antimicrobial activity, orcombinations thereof. For example, in some embodiments, thebioresorbable component 130 may be configured to modulate proteaseactivity. For example, contact with a wound fluid, such as woundexudate, may cause the bioresorbable component 130 to break down intoproducts that may have the effect of modulating protease activity.Modulating protease activity may include inhibiting protease activity,in some embodiments. For example, the disintegration, degradation,and/or dissolution products of collagen and/or ORC may be effective toinhibit the activity of destructive enzymes such as neutrophil elastaseand matrix metalloproteinase (MMP). In various embodiments, thebioresorbable component 130 may be effective to inhibit proteaseactivity such that protease activity is decreased to less than about 75%of the protease activity than would be present if uninhibited, or toless than about 50%, or to less than about 40%, or to less than about30% to less than about 20% of the protease activity that would bepresent if uninhibited.

In various embodiments, the bioresorbable composition may be essentiallyfree of water. For example, in some embodiments, the bioresorbablecomposition contains 10% or less, 8% or less, or 5% or less, of water.In some embodiments, the bioresorbable component 130 may be freezedried, such as through lyophilization, for example.

Degradation-Modulating Component

Generally, in some embodiments, the degradation-modulating component 140may be configured to modulate degradation of the bioresorbable component130. Modulating degradation may include controlling, regulating,delaying, impeding, reducing, increasing, or encouraging degradation, orcombinations thereof, for example, for a period of time after thedressing 102 is positioned with respect to a tissue site.

In some embodiments the degradation-modulating component 140 may beconfigured to modulate the communication of a physiological fluid, suchas wound exudate or blood, from an environment to the bioresorbablecomponent 130. Not intending to be bound by theory, by modulating thecommunication of a physiological fluid to the bioresorbable component130, the degradation-modulating component 140 may be effective tomodulate the degradation of the bioresorbable component 130. Forexample, in some embodiments, the degradation-modulating component 140may comprise, be configured as, or otherwise form a structural barrierto fluid communication to one or more surfaces of the bioresorbablecomponent 130. Additionally or alternatively, the degradation-modulatingcomponent 140 may be configured as a structural support effective tophysically support the bioresorbable component 130. Not intending to bebound by theory, by structurally supporting the bioresorbable component130, the degradation-modulating component 140 may extend the durationover which the bioresorbable component 130 exhibits structuralintegrity.

In some embodiments, the degradation-modulating component 140 may beconfigured to modulate degradation of the bioresorbable component 130for a predetermined interval, until a predetermined condition, orcombinations thereof. In some embodiments, the degradation-modulatingcomponent 140 may be configured to control fluid communication to orfrom the bioresorbable component 130 and/or to structurally support thebioresorbable component 130 for a predetermined interval, until apredetermined condition, or combinations thereof.

In some embodiments, the degradation-modulating component 140 maycomprise or be formed at least partially from a suitable composition,which may be referred to herein as a degradation-modulating composition.In some embodiments, the degradation-modulating composition may befurther configured such that a degradation-modulating component 140 may,upon the passage of the predetermined interval and/or upon theoccurrence of the predetermined condition, dissolve, dissociate,degrade, break down, undergo a structural change, or otherwise losestructural integrity, for example, such that the degradation-modulatingcomponent 140 does not continue to modulate degradation of thebioresorbable component 130.

In some embodiments, the degradation-modulating component 140 may becharacterized as biodegradable and/or as exhibiting biodegradability.For example, in some embodiments, the degradation-modulating component140 may be configured to exhibit a particular proportion ofdisintegration, degradation, or dissolution within a particular timeperiod. For instance, in various embodiments the degradation-modulatingcomponent 140 may be configured such that about 90% by weight, or about95% by weight, or about 99% by weight, or about 100% by weight of thedegradation-modulating component 140 may be disintegrated, degraded, ordissolved within a time period of from about 24 hours to about 150hours, or from about 36 hours to about 120 hours, or from about 48 hoursto about 96 hours, from contact with a physiological fluid, for example,an aqueous fluid such as blood or wound exudate, at a temperature ofabout 37° C. In some embodiments, the degradation-modulating component140 may be configured to disintegrate, degrade, or dissolve over anextended duration relative to the bioresorbable component 130. Forexample, the degradation-modulating component 140 may be configured todisintegrate, degrade, or dissolve, at a slower rate than thebioresorbable component 130, for example, such that a given volume ofthe degradation-modulating component 140 may be configured todisintegrate, degrade, or dissolve over a duration that is greater thana duration over which the same volume of the bioresorbable component 130will disintegrate, degrade, or dissolve. For example, thedegradation-modulating component 140 may be configured to disintegrate,degrade, or dissolve at a rate that is less than about 70%, or less thanabout 60%, or less than about 50%, or less than about 40%, or less thanabout 30%, or less than about 20 of a rate at which the bioresorbablecomponent 130 will disintegrate, degrade, or dissolve.

Additionally or alternatively, in some embodiments thedegradation-modulating component 140 may be configured to exhibit aparticular proportion of disintegration, degradation, or dissolutionupon the occurrence of a predetermined condition, such as when presentwithin an environment including an enzyme, for example, a protease. Insuch an embodiment, the degradation-modulating component 140 may beconfigured to exhibit an increased rate of disintegration, degradation,or dissolution in the presence of protease, for example, thedegradation-modulating component may be configured to disintegrate,degrade, or dissolve at about 10% less time than in the absence of aprotease, or about 20% less time, or about 25% less time, or about 30%less time, or about 35% less time, or about 40% less time, or about 45%less time, or about 50% less time.

In some embodiments, the degradation-modulating composition may comprisea polymer configured to dissolve, dissociate, degrade, break, undergo astructural change, or otherwise lose structural integrity, upon passageof the predetermined interval and/or upon the occurrence of thepredetermined condition. The dissolution, dissociation, degradation,breakage, occurrence of a structural change, or other loss of structuralintegrity of the polymer may be the result of various physical and/orchemical reactions, for example, degradation of polymer backbone,degradation or alteration of polymeric side-chains, loss ofcross-linking between polymer chains, state changes of the polymer(e.g., becoming a gel, becoming liquideous, dissolving in anotherliquid, swelling, or the like), or combinations thereof. For example,the degradation-modulating composition may comprise a polymer that iswater-soluble.

The term “polymer” may refer generally to the combined products of asingle chemical polymerization reaction. For example, polymers may beproduced by combining monomeric subunits into a covalently bonded chain.Polymers generally including a single type of monomeric repeating unitmay be referred to as “homopolymers,” and polymers including two or moretypes of monomeric repeating units may be referred to as “copolymers.”For example, the term “copolymer” may include products that are obtainedby copolymerization of two monomeric species, those obtained from threemonomeric species (e.g., terpolymers), those obtained from fourmonomeric species (e.g., quaterpolymers), etc. In various embodiments, apolymer may have different regions along its length, for example,differing as to the arrangement of the component monomer units.

In some embodiments, suitable examples of polymers that may be includedin the degradation-modulating composition forming or partially-formingthe degradation-modulating component 140 may include those polymershaving one or more suitable monomeric units. In some embodiments themonomeric unit present in the polymer may be derived from anothermonomeric unit that has been modified, for example, functionalized,after polymerization. In some embodiments, the monomeric unit maycomprise vinyl pyrrolidone, vinyl alcohol (for example, which may bederived from vinyl acetate), ethylene oxide, propylene oxide, ethyleneglycol, acrylic acid, a salt of acrylic acid, an ester of acrylic acid,acrylamido methylpropane sulphonic acid, a salt of acrylamidomethylpropane sulphonic acid, an ester of acrylamido methylpropanesulphonic acid, cellulose derivatives, copolymers thereof, blends ormixtures thereof, and combinations thereof. In some embodiments, thesemonomeric units may be present as a repeating unit or, additionally oralternatively, the monomeric unit may be present in a repeating unitcomprising two, three, or more monomers, for example, as part of adimer, trimer, or other oligomer. The term “repeating unit” generallyrefers to a fragment of a polymer that, when repeated, forms at least aportion of a polymer chain, for example, a single repeated monomerresidue or a repeated sequence of two or more monomer residues. In someembodiments, at least a portion of the polymers that may be included inthe degradation-modulating composition forming or partially-forming thedegradation-modulating component may be cross-linked. For example, thepolymer may comprise polyvinyl pyrrolidone, polyvinyl alcohol,polyethylene glycol, polypropylene glycol, poly(acrylic acid), orpoly(acrylamido methylpropane sulphonic acid).

In some embodiments, the polymers that may be included in thedegradation-modulating composition forming or partially-forming thedegradation-modulating component may be characterized as having anon-crosslinked, average molecular mass in the range of from about25,000 Daltons to about 2,000,000 Daltons, or from about 50,000 Daltonsto about 1,000,000 Daltons, or from about 75,000 Daltons to about750,000 Daltons. Additionally or alternatively, in some embodiments thepolymers that may be included in the degradation-modulating compositionforming or partially-forming the degradation-modulating component may becharacterized as having an average number of repeating units rangingfrom about 10 to 50,000, or from about 1,000 to about 40,000, or fromabout 2,500 to about 30,000.

Configurations of Bioresorbable Component and Degradation-ModulatingComponent

In various embodiments, the bioresorbable component 130 and thedegradation-modulating component 140 may have any suitableconfiguration. For example, in some embodiments, the bioresorbablecomponent 130 and the degradation-modulating component 140 may bepresent in separate, distinct layers. In some embodiments, a separateand distinct layer of the degradation-modulating component 140 may bepositioned adjacent to at least one bioresorbable component 130, whichmay also be configured as a separate, distinct layer. For example, thedegradation-modulating component 140 may at least partially cover orencapsulate the bioresorbable component 130. Additionally, in someembodiments, the degradation-modulating component 140 may also beconfigured to hold two adjacent bioresorbable components 130 together.

For example, FIG. 2 illustrates an embodiment of a dressing 200comprising a manifold 120, two degradation-modulating componentsconfigured as a first degradation-modulating layer 241 and a seconddegradation-modulating layer 242, and a bioresorbable componentconfigured as a bioresorbable layer 230. In the embodiment of FIG. 2 ,the first degradation-modulating layer 241 and the seconddegradation-modulating layer 242 may be positioned adjacent to thebioresorbable layer 230, for example, such that the firstdegradation-modulating layer 241 and the second degradation-modulatinglayer 242 may modulate the communication of a physiological fluid from atissue site to one or more surfaces of the bioresorbable layer 230. Insome embodiments, the first degradation-modulating layer 241, the seconddegradation-modulating layer 242, or both may comprise pores,perforations, apertures, or the like, for example, to allow fluidcommunication to the bioresorbable layer 230, for example, at apredetermined rate.

Additionally or alternatively, in some embodiments the dressing 102 maycomprise any suitable number of degradation-modulating layers. Forexample, FIG. 3 illustrates an embodiment of a dressing 300 comprising amanifold 120, four degradation-modulating components configured as afirst degradation-modulating layer 341, a second degradation-modulatinglayer 342, a third degradation-modulating layer 343, and a fourthdegradation-modulating layer 344, and three bioresorbable componentsconfigured as a first bioresorbable layer 331, a second bioresorbablelayer 332, and a third bioresorbable layer 333. In the embodiment ofFIG. 3 , the first degradation-modulating layer 341 and the seconddegradation-modulating layer 342 may be positioned adjacent to the firstbioresorbable layer 331, for example, such that the firstdegradation-modulating layer 341 and the second degradation-modulatinglayer 342 may modulate the communication of a physiological fluid from atissue site to surfaces of the first bioresorbable layer 331. Similarly,the second degradation-modulating layer 342 and the thirddegradation-modulating layer 343 may be positioned adjacent to thesecond bioresorbable layer 332, and the third degradation-modulatinglayer 343 and the fourth degradation-modulating layer 344 may bepositioned adjacent to the third bioresorbable layer 333, for example,such that the second degradation-modulating layer 342, the thirddegradation-modulating layer 343, the fourth degradation-modulatinglayer 344 may modulate the communication of a physiological fluid from atissue site to surfaces of the second bioresorbable layer 332 and thethird bioresorbable layer 333. In some embodiments, the dressing 102 maysimilarly include any desired number of alternatingdegradation-modulating layers and bioresorbable layers, for example,such that a degradation-modulating layer is adjacent to one or morebioresorbable layers.

Additionally or alternatively, in some embodiments, thedegradation-modulating component 140 may encapsulate the bioresorbablecomponent 130, for example, to form a single layer. For example, FIG. 4illustrates an embodiment of a dressing 400 comprising the bioresorbablecomponent 130 encapsulated in the degradation-modulating component 140to form a dressing layer 410. For example, the degradation-modulatingcomponent 140 may modulate the communication of a physiological fluidfrom a tissue site to the surfaces of the bioresorbable component 130.

Additionally or alternatively, in some embodiments the bioresorbablecomponent 130 may be incorporated within the degradation-modulatingcomponent 140. For example, the degradation-modulating component 140 maycoat the bioresorbable component 130 in various particulate forms, suchas fibers. For example, FIG. 5 illustrates an embodiment of a dressing500 comprising a dressing layer 510 and the manifold 120. In theembodiment of FIG. 5 , the bioresorbable component may be configured asfibers 530 in the dressing layer 510. The fibers 530 may be incorporatedwithin the degradation-modulating component 140. For example, thedegradation-modulating component 140 may comprise a coating on thefibers 530, and the coating can modulate the communication of aphysiological fluid from a tissue site to the fibers 530.

Additionally or alternatively, in some embodiments thedegradation-modulating component 140 may comprise, be configured as, orotherwise form a substrate or scaffold that may support thebioresorbable component 130. For example, in various embodiments, thedegradation-modulating component 140 may comprise or be configured as asubstrate such as a mesh, a lattice, a webbing, a woven or non-wovenarrangement of fibers, or the like. The degradation-modulating componentmay be applied to or incorporated within the bioresorbable component130.

For example, FIG. 6 illustrates an embodiment of a dressing 600comprising a dressing layer 610 and the manifold 120. In the embodimentof FIG. 6 , the dressing layer 610 may comprise a degradation-modulatingcomponent configured as a scaffold 640. The dressing layer 610 may alsocomprise a bioresorbable component configured as a substrate 630physically supported by the scaffold 640. For example, the scaffold 640may be applied to and/or at least partially embedded within thesubstrate 630. For example, the scaffold 640 may regulate degradation,disintegration, or other losses of structural integrity of the substrate630, for example, thereby regulating degradation of the bioresorbablecomponent.

In various embodiments, the dressing 102 may comprise any suitablenumber of the bioresorbable components 130, for example, two, three,four, five, six, seven, or more bioresorbable components 130. In someembodiments, a configuration, composition, or other parameter of a givenof the bioresorbable component 130 may be selected independently of,alternatively to, or dependent upon the configuration, composition, orother parameter of another of the bioresorbable component 130. Forexample, in some embodiments, the dressing 102 may be configured toprovide a predetermined wear-time, such as a duration over which thebioresorbable component 130 present within the dressing 102 remaineffective to provide biological activity, such as protease-inhibitingactivity, antimicrobial activity, or combinations thereof.

For example, the predetermined wear-time of the dressing 102 may bevaried dependent upon the number of bioresorbable components 130, theconfiguration of the various bioresorbable components 130, the number ofdegradation-modulating components 140, and the configuration of thevarious degradation-modulating components 140. Additionally, thepredetermined interval after which a given degradation-modulatingcomponent 140 may be configured to dissolve, dissociate, degrade, break,undergo a structural change, or otherwise lose structural integrity maybe manipulated by varying one or more parameters of thatdegradation-modulating component 140 and/or the degradation-modulatingcomposition forming that degradation-modulating component 140. Forexample, various predetermined intervals may be achieved by manipulatingthickness of the degradation-modulating component 140 the particularpolymers or combination of polymers forming the degradation-modulatingcomposition; the chain-length of the polymers forming thedegradation-modulating composition; the presence or degree ofcross-linking between various polymer chains within thedegradation-modulating composition; or combinations thereof. In variousembodiments, the dressing may be configurable to provide a wear-timefrom about 3 days to about 12 days, or from about 5 days to about 10days, or from about 6 days to about 8 days.

Methods

In operation, for example, in the context of a negative-pressuretherapy, the dressing 102 may be placed within, over, on, or otherwiseproximate to a tissue site, for example, a wound. The cover 106 may beplaced over the manifold 120 and the bioresorbable component 130 and thecover 106 sealed to an attachment surface near the tissue site. Forexample, the cover 106 may be sealed to undamaged epidermis peripheralto a tissue site. In some other embodiments, the dressing 102 may bepreassembled, for example, such that the bioresorbable component 130,manifold 120, and cover 106 are positioned with respect to each otherprior to placement proximate the tissue site or, alternatively, thevarious components of the dressing 102 may be positioned with respect tothe tissue site sequentially. Thus, the dressing 102 can provide asealed therapeutic environment, for example, a sealed space like sealedspace 107, proximate to a tissue site, substantially isolated from theexternal environment.

The negative-pressure source 104 may be used to reduce the pressure insuch sealed therapeutic environment. For example, negative pressureapplied across the tissue site, for example, via the dressing 102 caninduce macrostrain and microstrain in the tissue site, as well as removeexudates and other fluids from the tissue site, which can be collectedin container 112.

Advantages

In some embodiments, the dressings, the various combinations of dressingcomponents, and systems may be advantageously employed in the context ofnegative-pressure therapy, for example, to provide a dressing exhibitingextended wear-time. For example, the bioresorbable component of thedressing may be adapted to be resorbed after a predetermined duration,for example, in the range of from several days to a few weeks. In someembodiments, the bioresorbability characteristics of the bioresorbablecomponent allow the dressing to be left in place at the recipient sitefor substantial periods of time. For example, and not intending to bebound by theory, because the bioresorbable component of the dressing maybe bioresorbable, the dressing does not necessitate removal, forexample, to avoid in-growth of tissue (e.g., to ensure that the growingtissue at the recipient site does not become attached to thebioresorbable component). The capability to leave the dressing in placefor longer periods of time can yield several advantages. For instance,by leaving the dressing in place, premature removal, potentiallyresulting in disturbance of or trauma to the tissue growth, may beavoided. Also, by leaving the dressing in place, trauma to the tissuesite that would otherwise result from removal can be avoided.Additionally, leaving the dressing in place for sustained time periodsmay yield improved tissue growth.

Additionally, in some embodiments, the extended wear-time may allow thebioresorbable component to exhibit activity, such as protease-modulatingactivity, over the extended duration. For example, in operation, thedegradation-modulating component may be effective to modulate (e.g.,slow) the rate at which the bioresorbable component is resorbed and,thus, allow the bioresorbable component to exhibit activity, such asprotease-modulating activity, over the extended duration. Further still,in some embodiments where the dressing comprises multiple bioresorbablecomponents, the degradation-modulating component may be configured suchthat the various bioresorbable components (e.g., layers) may be resorbedat different, sequential intervals. For example, a firstdegradation-modulating component may be configured to modulatedegradation of a first bioresorbable component such that the firstbioresorbable component may be resorbed within a first time interval anda second degradation-modulating component may be configured to modulatedegradation of a second bioresorbable component such that the secondbioresorbable component may be resorbed within a second time interval.As such, and not intending to be bound by theory, by configuring thevarious bioresorbable components such that the various bioresorbablecomponents provide activity (e.g., protease-modulating activity) overdiffering intervals, the dressing, cumulatively, may provide activity(e.g., protease-modulating activity) over an extended duration.

The term “about,” as used herein, is intended to refer to deviations ina numerical quantity that may result from various circumstances, forexample, through measuring or handling procedures in the real world;through inadvertent error in such procedures; through differences in themanufacture, source, or purity of compositions or reagents; fromcomputational or rounding procedures; and the like. Typically, the term“about” refers to deviations that are greater or lesser than a statedvalue or range of values by 1/10 of the stated value(s), e.g., ±10%. Forinstance, a concentration value of “about 30%” refers to a concentrationbetween 27% and 33%. Each value or range of values preceded by the term“about” is also intended to encompass the embodiment of the statedabsolute value or range of values. Whether or not modified by the term“about,” quantitative values recited in the claims include equivalentsto the recited values, for example, deviations from the numericalquantity, but would be recognized as equivalent by a person skilled inthe art.

The appended claims set forth novel and inventive aspects of the subjectmatter disclosed and described above, but the claims may also encompassadditional subject matter not specifically recited in detail. Forexample, certain features, elements, or aspects may be omitted from theclaims if not necessary to distinguish the novel and inventive featuresfrom what is already known to a person having ordinary skill in the art.Features, elements, and aspects described herein may also be combined orreplaced by alternative features serving the same, equivalent, orsimilar purpose without departing from the scope of the inventiondefined by the appended claims.

1. A dressing comprising: a manifold; a bioresorbable component; and adegradation-modulating component covering two or more surfaces of thebioresorbable component and configured to modulate degradation of thebioresorbable component.
 2. The dressing of claim 1, wherein themanifold comprises a hydrophobic, open-cell foam.
 3. The dressing ofclaim 1, wherein the manifold is formed from polyurethane.
 4. Thedressing of claim 1, wherein the bioresorbable component exhibitsprotease-modulating activity.
 5. The dressing of claim 1, wherein thebioresorbable component comprises collagen and oxidized, regeneratedcellulose.
 6. The dressing of claim 1, wherein thedegradation-modulating component comprises a polymer having a monomericunit, wherein the monomeric unit comprises vinyl pyrrolidone, vinylalcohol, ethylene oxide, propylene oxide, ethylene glycol, acrylic acid,a salt of acrylic acid, an ester of acrylic acid, acrylamidomethylpropane sulphonic acid, a salt of acrylamido methylpropanesulphonic acid, an ester of acrylamido methylpropane sulphonic acid,cellulose derivatives, copolymers thereof, blends or mixtures thereof,or combinations thereof.
 7. The dressing of claim 1, wherein thedegradation-modulating component comprises a polymer made from vinylpyrrolidone.
 8. The dressing of claim 7, wherein thedegradation-modulating component comprises a copolymer of polyvinylpyrrolidone and vinyl acetate.
 9. The dressing of claim 1, wherein thedegradation-modulating component comprises cross-linked polymers. 10.The dressing of claim 1, wherein the degradation-modulating component iswater-soluble.
 11. The dressing of claim 1, wherein the dressingcomprises a first bioresorbable layer, a first degradation-modulatinglayer, and a second degradation-modulating layer, wherein the firstbioresorbable layer is disposed between the first degradation-modulatinglayer and the second degradation-modulating layer, and wherein thesecond degradation-modulating layer is disposed between the firstbioresorbable layer and the manifold.
 12. The dressing of claim 11,wherein the dressing further includes a second bioresorbable layer and athird degradation-modulating layer, wherein the second bioresorbablelayer is disposed between the second degradation-modulating layer andthe third degradation-modulating layer, and wherein the thirddegradation-modulating layer is disposed between the secondbioresorbable layer and the manifold.
 13. The dressing of claim 1,wherein the degradation-modulating component is disposed within thebioresorbable component.
 14. The dressing of claim 13, wherein thedegradation-modulating component encapsulates the bioresorbablecomponent.
 15. The dressing of claim 13, wherein the bioresorbablecomponent includes a plurality of bioresorbable fibers and thedegradation-modulating component includes a degradation-modulatingcoating that covers the plurality of bioresorbable fibers. 16-49.(canceled)